The present invention generally relates to image recording apparatuses for use in facsimiles, personal computers, copiers, and the like, and more particularly to a xerographic image recording apparatus having a toner recovery tank and a toner supply tank combined with each other to form a unitary, disposable magazine.
FIG. 1 shows a conventional xerographic image recording apparatus for recording an image on a recording sheet.
Referring to FIG. 1, the image recording apparatus comprises a photosensitive belt 1 driven along a circuitous path by a drive roller 2 in a direction indicated by an arrow. The photosensitive belt 1 is charged uniformly by a precharger unit 3 and is irradiated by an optical beam exiting from an exposure unit 4. The optical beam is produced by a laser device not illustrated as a laser beam in response to an image signal representing the image to be recorded and is deflected by a rotary polygonal mirror 5 forming a part of the exposure unit 4. The deflected laser beam is then passed through an optical system comprising a mirror and a cylindrical lens 6 and focused on the photosensitive belt 1. Thereby, an electrostatic latent image is formed on the photosensitive belt 1.
On the photosensitive belt 1 thus charged and formed with the electrostatic latent image, toner that is supplied from a toner tank 8 via a hopper mechanism 9 is coated by a development roller 7. Thereby the electrostatic latent image of the photosensitive belt 1 is developed. The hopper 9, the development roller 7 and other related parts form a developing unit 10.
Further, there is provided a sheet cartridge 11 wherein a number of recording sheets 12 cut into a predetermined size and shape are stacked. Upon the mounting of the cartridge 11 on the recording apparatus, the sheets 12 in the cartridge 11 are separated one by one from the stack by a feed roller 14 and a separator roller 15, and the sheet thus separated is passed along a path for recording the image. The feeding of each of the sheets is controlled by a pair of register rollers 16 that supply the sheet in synchronization with the feeding of the photosensitive belt 1 such that the developed toner image on the photosensitive belt 1 is transferred to the sheet at a predetermined position.
In order to transfer the toner image on the photosensitive belt 1 to each of the recording sheets, there is provided a transfer charger 17, and the sheet thus transferred with the toner image is then passed through a fixing unit 18 that has a heating element therein and comprises a pair of cooperating rollers. Thereby, the image transferred on the sheet is fixed and the recording of the image on the recording sheet is completed. Each of the recording sheets 12 is then discharged on a tray 21 by a discharge roller 19.
After the transfer of the toner image is completed, the photosensitive belt 1 is subjected to a cleaning process wherein a cleaning blade 22, which comes in contact with the photosensitive belt 1, removes any remaining toner on the photosensitive belt 1. The toner thus removed from the photosensitive belt 1 falls into a toner recovery tank 23. The cleaning blade 22 and the toner recovery tank 23 form a cleaning unit.
The photosensitive belt 1 thus subjected to the cleaning process is then passed through an electrostatic discharge station 24 that is formed from a lamp, and the electric charges remaining on the belt 1 are removed by irradiating light thereon. Thereby, the belt 1 is ready for the next recording operation.
In this conventional example, the exposure unit 4, the precharger unit 3, the electrostatic discharge station 24, the photosensitive belt 1, the feed rollers cooperating therewith, and other cooperating units such as the cleaning unit 20, are assembled to form a rotatable upper unit of the recording apparatus such that the upper unit is rotatable with respect to a lower fixed unit of the recording apparatus, about a pivot 25. Thus, when one of the sheets 12 becomes jammed in the sheet feeding path, the user can open the recording apparatus by opening the rotatable upper unit and remove the sheet that is causing the jam.
In such a conventional xerographic image recording apparatus, the lifetime of the photosensitive belt and the developing unit has reached a length of about several tens of thousands of hours when the standard A4 size sheet is used for recording. On the other hand, the toner in the toner supply tank cannot last such a long time because of the limited capacity of the toner supply tank. Because of the need to reduce the size of the recording apparatus, the size of the toner supply tank is limited. The same holds true for the toner recovery tank. Thus, the user of the recording apparatus has to replace the toner supply tank 8 and the toner recovery tank 23 frequently.
In the foregoing conventional recording apparatus, the toner recovery tank 23 and the toner supply tank 8 are provided separately, and because of this, they have to be separately replaced. Thus, the user is alerted to monitor the state of the toner supply tank 8 and the toner recovery tank 23 constantly, and when it is detected that either the toner supply tank 8 is empty or the toner recovery tank 23 is full, the tank is replaced. For this purpose, there is provided a toner sensor 26 in the hopper mechanism 9, as shown in FIG. 2, for detecting the existence of the toner supplied from the tank 8 for recording the image. Further, there is provided a toner sensor 27 in the toner recovery tank 23 for detecting when the collected toner has filled the toner recovery tank 23. Typically, a piezoelectric sensor is employed for each of the sensors 26 and 27 such that the piezoelectric sensor detects the dilatation or contraction of a rubber membrane 28 or 29 caused in response to the toner in the tank. The bar 30 in FIG. 2 is employed for stirring the tone in the tank 8.
Anyway, the user has to replace the tank 8 and the tank 23 separately at different times during use of the image recording apparatus and such a replacement operation is significantly troublesome for the user of the recording apparatus.
Although there is known a recording apparatus wherein the photosensitive body, the developing unit, the toner supply tank and the toner recovery tank are assembled as a unitary, disposable body, such an apparatus wastes resources as the still usable photosensitive body and the developing unit are disposed of upon the toner supply tank being replaced. As a result of this, the cost of the recording apparatus, including the operating cost, is inevitably increased. Further, the proposal of the photosensitive body causes contamination of the environment.